1. Field
The present embodiments relate to a non-contact magnetic sensor including a magnetoresistance element, and more particularly, to a magnetoresistance element which can be driven in a stable manner with a dipole irrespective of a polarity of an external magnetic field.
2. Related Art
A hall element, a magnetoresistance element, or the like are used in a non-contact magnetic sensor Since in the hall element, power consumption is high and hysteresis does not exist, it is required to install a hysteresis circuit or it is difficult to minimize a size of an element. Accordingly, a magnetic sensor using the magnetoresistance element is noticeable.
Magnetic sensors are used for detecting an open and close states of a foldable cellular phone and the like. For example, in related art, a magnetoresistance element and a fixed resistance element are coupled in series to output a potential, and an on-off switching signal is outputted according to a variation in output on the basis of a variation in magnetic field magnitude of an external magnetic field. When it is detected that the foldable cellular phone opens by outputting an on signal, for example, a backlight under a display is controlled so that the backlight emits light. The related art is disclosed in JP-A-8-17311 and JP-A-2003-60256.
However, in the method for detecting opening and closing, there is a following problem. That is, since a variation in resistance of the magnetoresistance element depends on a polarity of an external magnetic field, a direction of a magnet opposed to the magnetic sensor is limited. When the magnet is disposed in a direction opposite to a positive direction, the polarity of the external magnetic field is inverted and thus the resistance value of the magnetoresistance element is not changed according to the magnetic field magnitude of the external magnetic field in which the polarity is inverted. Accordingly, the open and close detection can not be properly performed.